The present invention is generally related to control of internal combustion engines, and, more particularly, the present invention is related to system and method for electronically controlling engine speed in vessels equipped with electronic fuel injection.
Vessels may be operated on large bodies of water, which may not be calm. For several reasons, such as fuel economy, passenger comfort or safety, equipment service life, etc., a cruising vessel may not be operated at a high rate of speed. Many times, water surface conditions, and not total available propulsion engine power, dictate the fastest practical vessel speed that may be achieved in the vessel.
Often traversing waves, ocean swells, variable ocean currents, depending on their magnitude and direction may cause undesirable fluctuations in vessel speed and consequently change the load on the propulsion engine, which in turn causes changes in engine speed. Changes of cargo distribution relative to the center of gravity of the vessel may also affect vessel speed. Further, changes in engine speed may affect power output at a given throttle setting for various reasons and aggravate the amount of change in engine speed and therefore vessel speed. Maintaining a constant or nearly constant cruising vessel speed is usually desirable but unfortunately may be difficult to achieve. Under some known techniques, the engine speed control desired to achieve a constant vessel speed may ,be attempted by manual adjustment of the throttle lever at the helm of the vessel. At best such techniques may only be partly effective since they may require human intervention, such as helmsman""s observation of engine speed meters, e.g., tachometers, in conjunction with manual adjustment of the throttle lever.
As will be understood by those skilled in the art, most modern relatively large marine engines for pleasure boats and other marine vessels may be operated from a helm station using remote engine controls with throttle and shift engine control inputs conveyed to the engine by mechanical push-pull cables. Unfortunately, even relatively minor variations in control mechanisms, control cables, control cable routing, and engine throttle control linkages, and the adjustments thereof can collectively result in substantial differences in mechanical efficiency between the remote control lever and the engine""s input signal device. Thus, in the case of known automated engine speed controllers, since these controllers generally rely on mechanically adjusting the respective throttle lever and throttle valve and associated cabling, these automated controllers tend to be expensive and unaffordable in small boat applications and subject to the above-described difficulties of having to provide mechanical control to a relatively inaccurate system.
In view of the foregoing issues, it should be appreciated that remote control of throttle lever position by mechanically controlling lever or handle position, either manually or automatically, can become unwieldy since such lever may have unsteady throttle control input and may fail to provide constant engine speed control. Thus, it is desirable to overcome the disadvantages of presently available remote engine control systems and to accurately control engine speed by utilizing microprocessor-based system and techniques to compare actual engine speed relative to a desired engine speed and adjust engine power output electronically, thus achieving substantially constant engine speed by electronically controlling engine power independent of the respective primary throttle control input signal supplied to each engine. It is believed that achieving substantially constant engine speed should result in less fluctuation of vessel speed regardless of ocean conditions.
Generally speaking, the foregoing needs are fulfilled by providing in one aspect of the present invention a computerized system for controlling an internal combustion engine. The system comprises a speed-setting device operable to supply a signal indicative of a desired engine speed. A speed sensor is coupled to the engine to supply a signal indicative of the actual speed of the engine. An electronic control unit is coupled to receive the respective signals indicative of desired engine speed and actual engine speed. The control unit in turn comprises a comparator configured to compare the respective signals indicative of desired and actual engine speed relative to one another and supply a comparator output signal based on the magnitude of any differences therebetween. A processor is responsive to the comparator output signal to adjust one or more engine operational parameters of the engine. The one or more engine operational parameters are responsive to respective control signals from the control unit to affect engine speed to reduce within a predefined range the magnitude of the differences between the actual and desired engine speed.
The present invention further fulfills the foregoing needs by providing in another aspect thereof a computer-readable medium encoded with computer program code for controlling a marine internal combustion engine responsive to a signal indicative of a desired engine speed. The engine has a speed sensor coupled to supply a respective speed sensor signal indicative of the actual speed of engine. The program code causes a computer to execute a method that allows for comparing the respective signals indicative of desired and actual engine speed relative to one another to supply a signal based on the magnitude of any differences therebetween. A processing step allows for processing the signal based on the magnitude of the differences between actual and desired engine speed to adjust one or more engine operational parameters of the engine. The method further allows for generating respective control signals to cause the one or more engine operational parameters to affect engine speed so as to maintain the actual engine speed within a predefined range relative to the desired engine speed.